"Full Stomach" Despite the Wait: Point-of-care Gastric Ultrasound at the Time of Procedural Sedation in the Pediatric Emergency Department

A convenient machine learning model to predict full stomach and evaluate the safety and comfort improvements of preoperative oral carbohydrate in patients undergoing elective painless gastrointestinal endoscopy

BACKGROUND AND AIMS

Assessment of the patient's gastric contents is the key to avoiding aspiration incidents, however, there is no effective method to determine whether elective painless gastrointestinal endoscopy (GIE) patients have a full stomach or an empty stomach. And previous studies have shown that preoperative oral carbohydrates (POCs) can improve the discomfort induced by fasting, but there are different perspectives on their safety. This study aimed to develop a convenient, accurate machine learning (ML) model to predict full stomach. And based on the model outcomes, evaluate the safety and comfort improvements of POCs in empty- and full stomach groups.

METHODS

We enrolled 1386 painless GIE patients between October 2022 and January 2023 in Nanjing First Hospital, and 1090 patients without POCs were used to construct five different ML models to identify full stomach. The metrics of discrimination and calibration validated the robustness of the models. For the best-performance model, we further interpreted it through SHapley Additive exPlanations (SHAP) and constructed a web calculator to facilitate clinical use. We evaluated the safety and comfort improvements of POCs by propensity score matching (PSM) in the two groups, respectively.

RESULTS

Random Forest (RF) model showed the greatest discrimination with the area under the receiver operating characteristic curve (AUROC) 0.837 [95% confidence interval (CI): 79.1-88.2], F1 71.5%, and best calibration with a Brier score of 15.2%. The web calculator can be visited at https://medication.shinyapps.io/RF_model/. PSM results demonstrated that POCs significantly reduced the full stomach incident in empty stomach group (p < 0.05), but no differences in full stomach group (p > 0.05). Comfort improved in both groups and was more significant in empty stomach group.

CONCLUSIONS

The developed convenient RF model predicted full stomach with high accuracy and interpretability. POCs were safe and comfortably improved in both groups, with more benefit in empty stomach group. These findings may guide the patients' gastrointestinal preparation.

Feasibility and Utility of Routine Point-of-Care Gastric Ultrasonography in Patients Undergoing Upper Gastrointestinal Endoscopy Procedures: A Prospective Cohort Study

OBJECTIVES

Previous studies have indicated that point-of-care ultrasonography (POCUS) of the gastric antrum can predict the adequacy of fasting before surgery and anesthesia. The aim of this study was to evaluate the utility of gastric POCUS in patients undergoing upper gastrointestinal (GI) endoscopy procedures.

METHODS

We performed a single-center cohort study in patients undergoing upper GI endoscopy. Consenting patient's gastric antrum was scanned before anesthetic care for endoscopy to determine the cross-sectional area (CSA) and qualitatively determine safe and unsafe contents. Further, an estimate of residual gastric volume was determined using the formula and the nomogram methods. Subsequently, gastric secretions aspirated during endoscopy were quantified and further correlated with nomogram and formula-based assessments. No patient required a change in the primary anesthetic plan except for using rapid sequence induction in those with unsafe contents on POCUS scans.

RESULTS

Qualitative ultrasound measurements consistently determined safe and unsafe gastric residual contents in 83 patients enrolled in the study. Unsafe contents were determined by qualitative scans in 4 out of 83 cases (5%) despite adequate fasting status. Quantitatively, only a moderate correlation was demonstrated between measured gastric volumes and nomogram (r = .40, 95% CI: 0.20, 0.57; P = .0002) or formula-based (r = .38, 95% CI: 0.17, 0.55; P = .0004) determinations of residual gastric volumes.

CONCLUSION

In daily clinical practice, qualitative POCUS determination of residual gastric content is a feasible and useful technique to identify patients at risk of aspiration before upper GI endoscopy procedures.

Ultrasonographic Evaluation of Gastric Content and Volume in Pediatric Patients Undergoing Elective Surgery: A Prospective Observational Study

Anesthesia-related complications, such as pulmonary aspiration of gastric contents, occur in approximately 0.02-0.1% of elective pediatric surgeries. Aspiration risk can be reliably assessed by ultrasound examination of the gastric antrum, making it an essential non-invasive bedside tool. In this prospective observational study, since most of our patients are immigrants and have communication problems, we wanted to investigate gastric contents and the occurrence of "high risk stomach" in children undergoing elective surgery for the possibility of pulmonary aspiration, even if the children and/or parents reported their last oral intake time. This risk is defined by ultrasound findings of solid content in the antrum and/or a calculated gastric volume exceeding 1.25 mL/kg. Children aged 2-18 were included in the study. Both supine and right lateral decubitus (RLD) ultrasound examinations were performed on the antrum before surgery. Using a qualitative grading scale from 0 to 2, we evaluated the gastric fluid content. The cross-sectional area (CSA) of the antrum was measured in the RLD position, aiding the calculation of the gastric fluid volume according to an established formula by Perlas. Ultrasound measurements of 97 children were evaluated. The median fasting duration was 4 h for liquids and 9 h for thick liquids and solids. Solid content was absent in all the children. Five children (5.2%) exhibited a grade 2 antrum, implying that fluid content was visible in both the supine and RLD positions. The median antral CSA in the RLD was 2.36 cm2, with a median gastric volume of 0.46 mL/kg. For patients with a grade 0 antrum, a moderate and positive correlation was observed between the antral CSA and BMI, and a strong and positive correlation was evident between the antral CSA and age, similar to a grade 1 antrum. Only a single child (1%) had a potentially elevated risk of aspiration of gastric contents. Hence, the occurrence of a "high risk stomach" was 1% (95% confidence interval: 0.1-4.7%) and is consistent with the literature. As a necessary precaution, we propose the regular use of ultrasound evaluations of gastric contents, given their non-invasive, bedside-friendly, and straightforward implementation, for identifying risks when fasting times are uncertain and for ruling out unknown risk factors in each potential patient.

Ultrasound assessment of residual gastric volume in older adults undergoing staged-bilateral total knee arthroplasty after consuming carbohydrate-containing fluids: a prospective observational study

BACKGROUND

We compared preoperative residual gastric volume (GV) between the first and second stages of total knee arthroplasty (TKA) in older adults after drinking carbohydrate-containing fluid 2 h prior to surgery.

METHODS

In this study, 36 patients, aged > 65 years, scheduled for staged bilateral TKA with one-week interval, were enrolled. The patients consumed 400 ml of carbohydrate-containing fluid 2 h prior to surgery. Before the induction of spinal anesthesia, the gastric antral cross-sectional area was measured at the first and second TKA using ultrasound, and the residual GV was calculated. The primary outcome was the residual GV. Qualitative GV (grades 0, 1, and 2) and analgesic consumption after the first TKA were assessed as secondary outcomes.

RESULTS

The GV (median [Q1, Q3]) was greater in the second-stage TKA (41.1 [22.5, 62.8] ml) than in the first-stage TKA (10.3 [0.0, 27.1] ml) (P < 0.001). In the qualitative assessment, the distribution was not different between the two stages of TKA (P = 0.219) and only one patient showed grade 2 gastric content in the second TKA. When opioid consumption was converted to an equivalent dose of morphine, an average of 53.9 mg of morphine was required after the first TKA.

CONCLUSIONS

Residual GV after drinking carbohydrate-containing fluid differed according to the stage of TKA, showing a larger residual GV in the second TKA than in the first one. In older adults scheduled to undergo bilateral staged TKA, caution is required in preoperative fasting practice, especially in second-stage surgery.

Gastric Point-of-Care Ultrasound in Acutely and Critically Ill Children (POCUS-ped): A Scoping Review

Introduction

Point-of-care ultrasound (POCUS) use is increasing in pediatric clinical settings. However, gastric POCUS is rarely used, despite its potential value in optimizing the diagnosis and management in several clinical scenarios (i.e., assessing gastric emptying and gastric volume/content, gastric foreign bodies, confirming nasogastric tube placement, and hypertrophic pyloric stenosis). This review aimed to assess how gastric POCUS may be used in acute and critically ill children.

Materials and Methods

An international expert group was established, composed of pediatricians, pediatric intensivists, anesthesiologists, radiologists, nurses, and a methodologist. A scoping review was conducted with an aim to describe the use of gastric POCUS in pediatrics in acute and critical care settings. A literature search was conducted in three databases, to identify studies published between 1998 and 2022. Abstracts and relevant full texts were screened for eligibility, and data were extracted, according to the JBI methodology (Johanna Briggs Institute).

Results

A total of 70 studies were included. Most studies (n = 47; 67%) were conducted to assess gastric emptying and gastric volume/contents. The studies assessed gastric volume, the impact of different feed types (breast milk, fortifiers, and thickeners) and feed administration modes on gastric emptying, and gastric volume/content prior to sedation or anesthesia or during surgery. Other studies described the use of gastric POCUS in foreign body ingestion (n = 6), nasogastric tube placement (n = 5), hypertrophic pyloric stenosis (n = 8), and gastric insufflation during mechanical ventilatory support (n = 4). POCUS was performed by neonatologists, anesthesiologists, emergency department physicians, and surgeons. Their learning curve was rapid, and the accuracy was high when compared to that of the ultrasound performed by radiologists (RADUS) or other gold standards (e.g., endoscopy, radiography, and MRI). No study conducted in critically ill children was found apart from that in neonatal intensive care in preterms.

Discussion

Gastric POCUS appears useful and reliable in a variety of pediatric clinical settings. It may help optimize induction in emergency sedation/anesthesia, diagnose foreign bodies and hypertrophic pyloric stenosis, and assist in confirming nasogastric tube placement, avoiding delays in obtaining confirmatory examinations (RADUS, x-rays, etc.) and reducing radiation exposure. It may be useful in pediatric intensive care but requires further investigation.

Ultrasound assessment of gastric contents in children before general anaesthesia for acute appendicitis

There is increasing evidence that a minority of adults with acute appendicitis have gastric contents, posing an increased risk of pulmonary aspiration. This study aimed to evaluate the proportion of children with acute appendicitis who have gastric contents considered to pose a higher risk of pulmonary aspiration. We analysed point-of-care gastric ultrasound data routinely collected in children before emergency appendicectomy in a specialist paediatric hospital over a 30-month period. Based on qualitative and quantitative antral assessment in the supine and right lateral decubitus positions, gastric contents were classified as 'higher-risk' (clear liquid with calculated gastric fluid volume > 0.8 ml.kg^-1 , thick liquid or solid) or 'lower-risk' of pulmonary aspiration. The 115 children studied had a mean (SD) age of 11 (3) years; 37 (32%; 95%CI: 24-42%) presented with higher-risk gastric contents, including 15 (13%; 95%CI: 8-21%) with solid/thick liquid contents. Gastric contents could not be determined in 13 children as ultrasound examination was not feasible in the right lateral decubitus position. No cases of pulmonary aspiration occurred. This study shows that gastric ultrasound is feasible in children before emergency appendicectomy. This technique showed a range of gastric content measurements, which could contribute towards defining the risk of pulmonary aspiration.

Pre-operative fasting in children: A guideline from the European Society of Anaesthesiology and Intensive Care

Current paediatric anaesthetic fasting guidelines have recommended conservative fasting regimes for many years and have not altered much in the last decades. Recent publications have employed more liberal fasting regimes with no evidence of increased aspiration or regurgitation rates. In this first solely paediatric European Society of Anaesthesiology and Intensive Care (ESAIC) pre-operative fasting guideline, we aim to present aggregated and evidence-based summary recommendations to assist clinicians, healthcare providers, patients and parents. We identified six main topics for the literature search: studies comparing liberal with conservative regimens; impact of food composition; impact of comorbidity; the use of gastric ultrasound as a clinical tool; validation of gastric ultrasound for gastric content and gastric emptying studies; and early postoperative feeding. The literature search was performed by a professional librarian in collaboration with the ESAIC task force. Recommendations for reducing clear fluid fasting to 1 h, reducing breast milk fasting to 3 h, and allowing early postoperative feeding were the main results, with GRADE 1C or 1B evidence. The available evidence suggests that gastric ultrasound may be useful for clinical decision-making, and that allowing a 'light breakfast' may be well tolerated if the intake is well controlled. More research is needed in these areas as well as evaluation of how specific patient or treatment-related factors influence gastric emptying.

Point-of-Care Ultrasound to Assess Gastric Content in Pediatric Emergency Department Procedural Sedation Patients

OBJECTIVES

There is debate regarding the timing of procedural sedation and analgesia (PSA) in relation to fasting status. Point-of-care ultrasound (POCUS) provides the ability to measure gastric content and is being used as a surrogate for aspiration risk in anesthesia. We sought to evaluate the gastric content of pediatric emergency department (PED) patients undergoing PSA using POCUS.

METHODS

We performed a prospective observational study using a convenience sample of pediatric patients undergoing PSA between July 1, 2018, and June 30, 2019. Following a brief history, gastric content was measured using POCUS in both supine and right lateral decubitus positions at 2-hour intervals until the time of PSA. Qualitative content and calculated volume were classified based on the Perlas Model of anesthesia "Risk" assessment.

RESULTS

Ninety-three patients were enrolled with 61.3% male and mean age of 6.5 years. Gastric content was determined in 92 patients. There were 79.3% that had "high risk" content at the time of PSA, with a median fasting time of 6.25 hours and no serious adverse events. Fasting duration had a weak to moderate ability to predict "risk" category (area under the curve = 0.73), with no patient (n = 17) who underwent multiple evaluations awaiting PSA progressing from "high" to "low risk."

CONCLUSIONS

The majority of PED patients undergoing PSA at our institution had "high risk" gastric content with no clinically significant change occurring during serial evaluations. This calls into question the utility of delaying PSA based upon fasting status and lends support to a more comprehensive risk-benefit approach when planning pediatric PSA.

Does Point-of-Care Gastric Ultrasound Correlate With Reported Fasting Time?

OBJECTIVE

Traditionally, patient-reported fasting time has been the primary objective presedation measure of aspiration risk. Recently, gastric ultrasound has been used to assess gastric volume for the determination of aspiration risk in patients undergoing anesthesia in the operative setting. We sought to determine the correlation of gastric volume estimated by point-of-care ultrasound (POCUS) to reported fasting time.

METHODS

We included children 4 to 18 years of age who presented with an acute traumatic injury. Enrolled children underwent POCUS to calculate gastric volume, which was calculated using a validated formula: Volume (mL) = -7.8 + (3.5 × Cross-sectional Area [CSA]) + (0.127 × Age in months). The CSA was measured (CSA = (anterior-posterior diameter × craniocaudal diameter × π)/4). We analyzed the relationship between time since last reported oral intake and measured gastric volume using Spearman rank correlation (ρ).

RESULTS

A total of 103 patients with a median age of 10.5 years (interquartile range, 7.3-13.7 years) were enrolled. The gastric antrum was identified and measured in 88 (85%) patients; air obstructing the posterior surface of the gastric antrum prevented measurement in 14 of the 15 remaining patients. We observed a weak inverse correlation between fasting time (either liquid or solid) and estimated gastric volume (ρ = -0.33), with no significant difference based on type of intake (solids, ρ = 0.28; liquids, ρ = 0.22).

CONCLUSION

Gastric volume can be estimated by POCUS and is not strongly correlated with fasting time in children in the emergency department setting.

Assessing gastric contents in children before general anesthesia for acute extremity fracture: An ultrasound observational cohort study

STUDY OBJECTIVE

Children with acute extremity fractures are commonly considered to be at risk of pulmonary aspiration of gastric contents during the induction of anesthesia. This study aimed to evaluate the proportion of such children with high-risk gastric contents using preoperative gastric ultrasound.

DESIGN

Prospective observational cohort study.

SETTING

Specialist pediatric center over a 30-month period.

PATIENTS

Children undergoing surgery within 24 h of an acute extremity fracture.

INTERVENTIONS

None.

MEASUREMENTS

According to preoperative qualitative and quantitative ultrasound analysis of the antrum in the supine and right lateral decubitus positions, gastric contents were classified as high-risk (clear liquid with calculated gastric fluid volume > 0.8 mL.kg^-1, thick liquid, or solid) or low-risk. Factors associated with high-risk gastric contents were identified by multivariable analysis.

MAIN RESULTS

Forty-one children (37%; 95% CI: 28-47) of the 110 studied (mean(SD) age: 10(3) years) presented with high-risk gastric contents, including 26 (24%; 95% CI: 16-33) with solids/thick liquid contents. Scanning in the supine position alone allowed a diagnosis of high-risk gastric contents in 23 children out of the 63 for whom right lateral decubitus positioning was unfeasible. Gastric contents remained undetermined in 41 children, including one with a non-contributory gastric US (antrum non-visualized). Proximal limb fractures (OR: 2.5; 95% CI: 1.0-6.2), preoperative administration of opioids (OR: 3.9; 95% CI: 1.1-13), and the absence of bowel sounds (OR: 8.0; 95% CI: 1.4-44) were associated with high-risk gastric contents. Performing surgery the day following the trauma was a protective factor (OR: 0.1; 95% CI: 0.0-0.6). No cases of pulmonary aspiration occurred.

CONCLUSIONS

At least one-third of children with an acute isolated extremity fracture had preoperative gastric contents identified as high risk for pulmonary aspiration. Although preoperative history can guide anesthetic strategy in this population, ultrasound allowed clear stratification of the risk of aspiration in most cases.

Utility of gastric ultrasound in evaluating nil per os status in a child

Although rare, the aspiration of gastric contents can lead to significant morbidity or even mortality in pediatric patients receiving anesthetic care. For elective cases, routine preoperative practices include the use of standard nil per os times to decrease the risk of aspiration. However, patients may fail to adhere to provided NPO guidelines or other patient factors may impact the efficacy of standard NPO times. Gastric point-of-care ultrasound provides information on the volume and quality of gastric contents and may allow improved patient management strategies. We present a 4-year-old patient who presented for bilateral myringotomy with tympanostomy tube insertion, who was found to have evidence of a full stomach during preoperative gastric ultrasound examination. The use of preoperative gastric point-of-care ultrasound in evaluating stomach contents and confirming NPO times is reviewed and its application to perioperative practice discussed.

Point-of-Care Ultrasound to Assess Gastric Content

Gastric ultrasound (US) is a growing modality within the point-of-care ultrasound (POCUS) field. It provides the ability to directly measure an individual patient's gastric content and has potential use as both a clinical and a research tool. Here, we review the historical development of current gastric US models and their clinical application within the field of general anesthesia, describe the US findings and technique for using POCUS to assess gastric content, and discuss the current and potential applications of gastric POCUS within the emergency department.

Point-of-care ultrasound in pediatric anesthesia: perioperative considerations

PURPOSE OF REVIEW

To review the perioperative applications of point-of-care ultrasound (POCUS).

RECENT FINDINGS

The role of point-of-care ultrasonography for perioperative care is expanding with respect to perioperative application. The imaging approach can complement the physical exam and provide additional information for decision-making in pediatric perioperative medicine. This review will focus on applications in the following organ systems: airway, cardiac, pulmonary and gastric. Specifically, POCUS of the airway has been used to optimize endotracheal tube depth, aid in tube size selection and predict difficulty with laryngoscopy and intubation. Lung POCUS has been used to assess for causes hypoxemia as well as to optimize ventilatory mechanics. Cardiac POCUS has been used for assessment of hemodynamics, valvular and ventricular function. Gastric ultrasound has emerged as an evaluative mechanism of gastric content in the setting of fasting as well as to confirm placement of gastric tubes. The applications of POCUS in the perioperative setting continue to evolve as a reliable diagnostic tool that can assist in timely diagnosis, improve procedural safety and has the potential to improve patient outcomes.

SUMMARY

The utility of perioperative POCUS has been well demonstrated, specifically for examination of the airway, stomach and cardiopulmonary system. It is advisable for the novice sonographer to perform POCUS within the guidelines set by the American Society of Echocardiography regarding basic POCUS. As with all diagnostic modalities, understanding the limitations of ultrasound and POCUS as well as continuous self-assessment is crucial.